Hydro-geomorphic influence on properties, classification and management considerations of soils on alluvial landforms in South-eastern Nigeria

Abstract

The soils were characterized with regards to their macro morphology, physicochemical properties and heavy metal contents. This is to infer their pedogenesis and propose agrotechnology transfers as well as management considerations necessary for sustainable cultivation. Reconnaissance survey was used for initial soil identification. Two categories of the flood plain soils were identified viz. the levee and the back-swamp. Three profile pits were dug on each identified category. The results showed that the soils on the back-swamps were poorly drained and the soils on the levee were well drained. Their colours varied from dull yellow (2.5 YR 6/5) to light gray (7.5YR 8/2) on the levee and dull reddish brown (5YR 6/3) to pale reddish orange (7.5YR 8/3) on the back-swamp. Mottling was observed in all the pits, indicating redoximorphism. Clay content was low to high and ranged from 4 to 30 %. It showed illuviation in the back-swamp. The soil pH was slightly acid. It has low exchangeable acidity of 0.2 to 5.83 cmol/kg and low cation exchange capacity ranging from 1.82 to 7.61cmol/kg. The low CEC values imply that the clay mineral dominant in the soils is non-expansible. The soils were not sodic as the mean values for exchangeable sodium percentage was <6 %. Prevailing pedogenic processes identified in the area, were eluviation, illuviation, gleization, pedoturbation, braunification, and leaching. The soils were classified as Entisols, suborder Psamment and inceptisols, suborder Ustepts and correlated in FAO/WRB as Fluvisols (Dystric fluvisols) and Gleysols. Management practices like drainage practices, use of organic manure to enhance the soil conditions were recommended.